Sahih al-Bukhari, Volume 9, Book 83, Hadith 48 (USC-MSA) ⓘ
Narrated Abu Huraira: The Prophet said, "There is no Diya for a person injured or killed by an animal (going about without somebody to control it) and similarly, there is no Diya for the one who falls and dies in a well, and also the one who dies in a mine. As regards the Ar-Rikaz (buried wealth), one-fifth thereof is for the state."
حَدَّثَنَا مُسْلِمٌ، حَدَّثَنَا شُعْبَةُ، عَنْ مُحَمَّدِ بْنِ زِيَادٍ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " الْعَجْمَاءُ عَقْلُهَا جُبَارٌ، وَالْبِئْرُ جُبَارٌ، وَالْمَعْدِنُ جُبَارٌ، وَفِي الرِّكَازِ الْخُمُسُ " .
also referenced under: Book 87, Hadith 51 (In-Book) & Hadith 6913 (DarusSalam)